From 9d87c925a9eaa4fc256be3173c14a20d1469472d Mon Sep 17 00:00:00 2001
From: fishsoupisgood <github@madingley.org>
Date: Wed, 9 Sep 2020 11:53:37 +0100
Subject: everything, mostly, working

---
 radiator-plc/stm32/app/ds18b20.c | 128 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 radiator-plc/stm32/app/ds18b20.c

(limited to 'radiator-plc/stm32/app/ds18b20.c')

diff --git a/radiator-plc/stm32/app/ds18b20.c b/radiator-plc/stm32/app/ds18b20.c
new file mode 100644
index 0000000..3bd63ed
--- /dev/null
+++ b/radiator-plc/stm32/app/ds18b20.c
@@ -0,0 +1,128 @@
+#include "project.h"
+
+#define DS18B20_CONVERT 0x44
+#define DS18B20_WRITE_SCRATCHPAD 0x4e
+#define DS18B20_READ_SCRATCHPAD 0xbe
+
+
+#define TIMEOUT 150
+
+
+unsigned extract_leu16 (uint8_t *d)
+{
+  uint32_t u;
+
+  u = (uint32_t) d[0] | (((uint32_t) d[1]) << 8);
+  return u;
+}
+
+
+int extract_les16 (uint8_t *d)
+{
+  uint32_t u;
+  u = extract_leu16 (d);
+
+  if (u & 0x8000) u |= 0xffff0000;
+
+  return (int) u;
+}
+
+
+/* do not call from interrupt context (ie ticker)*/
+int
+ds18b20_read_sp (const Onewire_addr *a, uint8_t *buf, unsigned len)
+{
+  if (onewire_reset_and_select (a))
+    return ~0U;
+
+  onewire_write_byte (DS18B20_READ_SCRATCHPAD);
+  onewire_read_bytes (buf, len);
+
+
+  if ((len == 9) && onewire_check_crc (buf, 8, buf[8]))
+    return ~0U;
+
+  return 0;
+}
+
+int
+ds18b20_write_sp (const Onewire_addr *a, uint8_t *buf, unsigned len)
+{
+  if (onewire_reset_and_select (a))
+    return ~0U;
+
+  onewire_write_byte (DS18B20_WRITE_SCRATCHPAD);
+  onewire_write_bytes (buf, len);
+
+  return 0;
+}
+
+int ds18b20_convert (const Onewire_addr *a, unsigned timeout)
+{
+
+  if (onewire_reset_and_select (a))
+    return ~0U;
+
+  onewire_write_byte (DS18B20_CONVERT);
+
+  if (timeout && onewire_wait_complete (timeout))
+    return ~0U;
+
+  return 0;
+}
+
+int
+ds18b20_set_12 (const Onewire_addr *a)
+{
+  uint8_t buf[9];
+
+
+  if (ds18b20_read_sp (a, buf, 9))
+    return 1;
+
+  buf[0] = 0x0;
+  buf[1] = 0x0;
+  buf[2] = 0x7f; /* 12 bit conversions */
+
+  return ds18b20_write_sp (a, buf, 3);
+
+}
+
+int ds18b20_read (const Onewire_addr *a, int *temp)
+{
+  uint8_t buf[9];
+
+  if (ds18b20_read_sp (a, buf, 9))
+    return 1;
+
+  *temp = (extract_les16 (buf) * 500) >> 3;
+  return 0;
+}
+
+
+int
+ds18b20_set_12_convert (const Onewire_addr *a)
+{
+
+  if (ds18b20_set_12 (a))
+    return 1;
+
+  if (ds18b20_convert (a, 0))
+    return 1;
+
+  return 0;
+}
+
+/* do not call from interrupt context (ie ticker)*/
+int
+ds18b20_set_12_convert_and_read (const Onewire_addr *a, int *temp)
+{
+  if (ds18b20_set_12 (a))
+    return 1;
+
+  if (ds18b20_convert (a, TIMEOUT))
+    return 1;
+
+  return ds18b20_read (a, temp);
+}
+
-- 
cgit v1.2.3